The primary objective of the proposed research is to assess the utility of a home-correspondence smoking cessation program in inducing women to stop smoking during pregnancy. Should the program prove successful from a behavior change perspective, a second objective will be to determine the impact of the program from a health and cost outcome perspective (i.e., did participants in the self-care program experience a reduced incidence of low birthweight/preterm deliveries and have reduced medical care expenditures as compared with a control group receiving standard prenatal medical care?). A final objective of the study will be to determine if the home-correspondence program is successful in encouraging abstinence from cigarette smoking over a prolonged period of time (i.e., up to six months postpartum). The site of the proposed research will be Maxicare, an HMO serving approximately 150,000 members in Southern California. A total of 540 pregnant smokers will be randomly assigned to either the Experimental Group or a Control Group which will receive standard prenatal medical care. Data to be obtained on the Experimental and Control Group subjects include: (1) a Self-Administered Baseline Questionnaire tapping sociodemographic characteristics, pregnancy history, smoking history, pregnancy and smoking-related health beliefs and attitudes, motivation to quit, perceived availability of social network support for quitting, etc.; (2) an End-Of-Pregnancy Phone Interview which will assess the subjects' smoking behavior during pregnancy and the range of methods used in the quitting process; and (3) a Six-Month Postpartum Phone Interview which will ascertain the duration of the smoking behavior change reported during pregnancy. These self-report data will be augmented by: (1) Multiple Urine Thiocyanate Tests which will provide an objective biochemical estimate of smoking status during pregnancy; (2) Infant Health Outcome Data, including birthweight, Apgar scores, incidence of birth defects, illnesses observed during the first 6 months of life, etc.; and (3) Hospital and Outpatient Medical Care Costs, including costs of care associated with the initial hospital stay of the infant, as well as ongoing pediatric treatment costs incurred during the first half year of life.